1. Field of the Invention
The present invention relates to an electronic device, and more particularly to a technique which is effectively applicable to an electronic device having a flexible printed circuit board such as a display device, for example.
2. Description of the Related Art
A liquid crystal display device (also referred to as “liquid crystal display module”) which includes a small-sized TFT (Thin Film Transistor)-type liquid crystal display panel has been popularly used as a display part of a portable device such as a mobile phone.
In general, a liquid crystal display device includes a liquid crystal display panel and a backlight which radiates light to the liquid crystal display panel. In a liquid crystal display device which is used as a display part of a portable device such as a mobile phone, a backlight is constituted of a resin frame mold (hereinafter, referred to as “mold”), a group of optical sheets which is arranged in the inside of the mold, a light guide plate, and a reflection sheet which is arranged below the light guide plate. Further, the liquid crystal display panel is constituted of a first substrate (for example, a glass substrate or the like), a second substrate, and liquid crystal which is sandwiched between the first substrate and the second substrate.
That is, the liquid crystal display device used in the mobile phone is configured such that the first substrate which constitutes the liquid crystal display panel is fixed to the frame-shaped mold by adhesion, and light radiated from the backlight arranged below the liquid crystal display panel is allowed to pass through the liquid crystal display panel. Here, a semiconductor chip which constitutes a driver IC for driving liquid crystal and a flexible printed circuit board (FPC) which transmits electricity and video data to the first substrate are adhered to the first substrate by way of an anisotropic conductive film.
FIG. 4 is a plan view of a conventional liquid crystal display device, and FIG. 5 is a bottom plan view of the conventional liquid crystal display device. Further, FIG. 6 is a cross-sectional view showing the cross-sectional structure taken along a line a-a′ in FIG. 4.
In FIG. 4 to FIG. 6, symbol 1 indicates an upper polarizer, symbol 2 indicates a second substrate (also referred to as “CF substrate”), symbol 3 indicates a first substrate (also referred to as “TFT substrate”), symbol 4 indicates a semiconductor chip, symbol 5 indicates a flexible printed circuit board (hereinafter, referred to as “FPC”), symbol 6 indicates a resin frame mold, symbol 7 indicates white light emitting diodes which function as a light source, symbol 8 indicates a light blocking tape, symbol 9 indicates a reflection sheet, symbol 10 indicates a light guide plate, symbol 11 indicates a group of optical sheets, and symbol 12 indicates a lower polarizer.
The FPC 5 which is adhered to respective terminals of the first substrate 3 of the liquid crystal display panel may be used in a straightly extending manner. However, in general, in a mobile phone or the like which does not have a large margin in a longitudinal size thereof, as shown in FIG. 4 and FIG. 5, it is often the case where the FPC 5 is used while being folded to a rear side of the resin frame mold 6. Here, the FPC 5 is connected to a phone body via an interface terminal portion 51. Further, a portion 52 of the FPC 5 which is folded to the rear side of the resin frame mold 6 is an LED mounting portion on which the white light emitting diodes 7 constituting a light source are mounted.
As shown in FIG. 4 and FIG. 5, in the conventional liquid crystal display panel, respective terminals formed on an edge portion of one side of the first substrate 3 and a wiring layer of the FPC 5 are connected to each other using an anisotropic conductive film (ACF) in general. Such a display device is disclosed in JP-A-7-92480.